1. Field of the Invention
The present invention relates to an apparatus for stacking a predetermined number of sheet members that are successively charged via a feed system in a stacking position, an apparatus for measuring dimensions of sheet members, and an apparatus for and a method of marking sheet members.
2. Description of the Related Art
There have been used packaged products each comprising a stack of sheet members, e.g., sheet-like photosensitive members such as X-ray films, which are packaged by a package film as a light shielding member. For producing such packaged products, it is customary to stack a predetermined number of sheet-like photosensitive members with a stacking device before the sheet-like photosensitive members are delivered to a next process such as a packaging process or the like.
In the stacking device, sheet-like photosensitive members are successively supplied to a stacking position by a feed system such as a belt conveyor or the like, and then successively dropped onto an lining cardboard, a product tray, or a stacking bottom plate. For example, Japanese laid-open patent publication No. 4-209158 discloses a sheet-like member stacking apparatus which has a sheet holding means for vertically stacking and holding a plurality of sheet-like members in a given stacking position, a sheet supply means for supplying sheet-like members substantially horizontally from a position near the stacking position to a position over the stacking position, and dropping the sheet-like members to the stacking position, and a suction means for pulling downwardly a rear end of the sheet supply means.
The suction means generates an air flow for lowering the rear end of a sheet-like member that is dropped to the stacking position by the sheet supply means. Since the air flow quickly lowers the rear end of the sheet-like member that is dropped by the sheet supply means, a succeeding sheet-like member does not hit the preceding sheet-like member. Thus, successive sheet-like members can smoothly and efficiently be stacked in the stacking position.
With the conventional sheet-like member stacking apparatus, sheet members cannot be delivered or expelled to a front stopper for limiting front end positions thereof if the speed for stacking sheet members is set to a relatively low value. A first sheet member to be stacked is liable to impinge upon an lining cardboard, a product tray, or a stacking bottom plate that is placed in the stacking position, making it difficult to stack a desired number of sheet members stably in the stacking position and also tending to cause damage to the sheet members which suffer a reduction in product quality.
There are known apparatus including an electronic flash lamp and an optical sensor for measuring dimensions of a sheet member that is being fed. These known apparatus include an apparatus for applying light from an electronic flash lamp toward a sheet member, detecting light reflected from the sheet member with a camera, and detecting the position of ends of the sheet to measure dimensions of the sheet member (see Japanese laid-open patent publication No. 4-9605, for example) and an apparatus having an electronic flash lamp and a sensor that are disposed one on each side of a sheet member feed path, the sensor detecting a position where light from the electronic flash lamp is blocked by a sheet member to measure dimensions of the sheet member (see Japanese laid-open patent publications Nos. 5-52526 and 6-147836, for example).
There has been a demand for the measurement of dimensions of a sheet-like photosensitive member with an apparatus having an electronic flash lamp and an optical sensor as described above. One problem with the apparatus used for measuring dimensions of a sheet-like photosensitive member is that when light from the electronic flash lamp is applied to the sheet-like photosensitive member, the sheet-like photosensitive member is apt to be fogged. Consequently, it has been difficult to use the apparatus for the purpose of measuring dimensions of a sheet-like photosensitive member.
Sheet-like photosensitive members are marked by a marking device with a latent image of a manufacturing lot number representing manufacturing information such as a processed sequence and an ISO sensitivity value representing the sensitivity of the sheet-like photosensitive member. The marked information is turned into a visible image when the sheet-like photosensitive member, such as an X-ray film, is processed by a developing process. The marked information becomes effective for the user if the X-ray film is defective, for example.
The marking device uses LEDs as light sources for emitting light with several colors as a means for marking desired letters or the like on X-ray films. For example, green light emitted from a green LED and red light emitted from a red LED are mixed into yellow light, which is applied to an X-ray film to mark the X-ray film with desired letters or the like. Each of the LEDs is connected to an LED driver for energizing the LED for light emission.
Since the marking device uses a plurality of LEDs, it also requires as many LED drivers as the number of LEDs, and hence necessarily becomes large in size. In addition, the marking device needs a complex control system for the LED drivers. The complex control system cannot easily be maintained and managed, and tends to increase the equipment cost of the marking device.
It is a general object of the present invention to provide an apparatus for smoothly and reliably stacking sheet members in a stacking position while effectively preventing the sheet members from being damaged.
A major object of the present invention is to provide an apparatus for measuring dimensions of sheet members without allowing the sheet members to be fogged.
Another major object of the present invention is to provide an apparatus for and a method of marking sheet members with desired letters or the like with only white LEDs, so that the cost of equipment used is reduced.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present invention are shown by way of illustrative example.